Among the parameters we can deduce from incoherent-scatter radar measurements in the thermosphere is the meridional wind - the horizontal neutral wind in the magnetic north-south direction. Since this was first realized in 1967, radar observations have contributed greatly to the study of thermospheric dynamics. At mid and low latitudes, they have shown the important impact that tides propagating upward, from the lower atmosphere, have on the dynamics at F-region altitudes. At high latitudes, radar measurements have demonstrated what effects momentum and energy transfer from the magnetosphere have on the dynamics at F-region altitudes; including local ion drag, equatorward surge near midnight, IMF By, local Joule heating, high-latitude heating, and midnight abatement and reversal. More generally the radar data have been used to confirm basic ideas about the global meridional circulation. Initially this was done with individual radars; now coordinated observations by a network of radars take data for periods of from one to five days. These global observations provide measurements of the full diurnal pattern at multiple locations as a function of season, magnetic activity, solar cycle, and of many other geophysical parameters. These multiday campaigns have contributed significantly to major ongoing programs such as CEDAR and WITS, and are planned to support future ones, such as STEP. The breadth of these programs is especially significant today. We are entering a new era when radar observations, combined with those from other instruments, can be used in conjunction with major theoretical models to test our quantitative understanding of the myriad physical processes and interactions that give rise to the winds and other geophysical parameters in the upper atmosphere.